1. Field of the Invention
This invention relates to a fuel cell for an automobile, house use or a mobile device, and a membrane electrode assembly (MEA) of the fuel cell.
2. Description of the Related Art
Fuel cells are attracting attention as a power supply system that hardly harms environment because water is the only by-product. In recent years, among various fuel cells, polymer electrolyte fuel cells (PEFCs) utilizing an ion exchange membrane, which has a proton conductivity, as an electrolyte membrane are considered promising as a power supply system for an automobile, house use and a mobile device because of a low operating temperature, high output density and ease of miniaturization.
Polymer electrolyte fuel cells can operate in a low temperature region. They are usually used at an operating temperature in the range of 80-100° C. and expected to be used as a power supply for an automobile or house use etc. A polymer electrolyte fuel cell (PEFC) is a battery having an assembled structure named membrane electrode assembly (MEA), in which a pair of catalyst electrode layers are arranged on both surfaces of a polymer electrolyte membrane, combined between a pair of separator plates, in one of which a flow path transferring a fuel gas such as hydrogen is formed and in the other of which a flow path supplying an oxidant gas such as oxygen is formed.    <Patent Document 1> JP-A-2002-063909
An MEA of a polymer electrolyte fuel cell needs to be humidified in order to maintain conductivity of the electrolyte membrane. It is desirable however that the fuel cell is operated with low humidification, or further, without humidification since the overall cost of the fuel cell system will increase because of the presence of a humidifier.